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Hack 85 Map the Wireless Landscape with NoCat Maps

Manage many wireless nodes with this open
source mapping project.

In addition to commercial tools like Topo!
and the DeLorme map software [Hack #80], there are a number of
freely available mapping solutions that make use of public GIS data.
While there is a huge amount of data available about the surface of
our planet, most of the tools used to query and view the data are far
from simple.

The NoCat Map project combines two powerful GIS programs to build a
sophisticated but easy-to-use node database. It is built on

MapServ
(http://mapserver.gis.umn.edu/)
and Grass (http://grass.itc.it/),
and is available at http://maps.nocat.net/. NoCat Maps integrates
the data and rendering functionality of MapServ and Grass with a
simple node database, and attempts to provide useful data and
visualization from the result. Users can add data for their own
equipment, including latitude, longitude, altitude, and contact
information. If this data isn't known ahead of time,
it can make an approximate guess from the user's
mailing address.

This data can then be queried and compared to other nodes in the
database to find likely point-to-point links. You can then select a
node from the database and view the likeliest links in a simple
table, as shown in Figure 6-4.

Since the position of each node is known, the distance and bearing
can easily be calculated. By consulting the GIS data for the land
elevation between the two nodes, a minimum clearance can also be
estimated. This can be shown graphically by clicking on the
"View Profile" link.

Figure 6-5 shows the profile of a possible link
between two points. Note that just as with other tools that rely on
GIS data, this shows the lay of the land without any indication of
ground clutter (buildings, trees, etc.). This is good enough to go on
for a rough estimate, and is especially helpful for eliminating
definite impossibilities (Figure 6-6).

NoCat Maps is a work in progress, and currently supports only data
for Sonoma County, CA. However, the source code is freely available,
as are the data sets for just about every location in the U.S. If you
are looking for an inexpensive method for managing a large number of
outdoor point-to-point links, this software could be just what you



want.